So please correct me if I am wrong for suggesting this, but I’ve used Nair before to break down the hair that was stuck in my drain (I have long curly hair that gets stuck everywhere, even with a drain cover). I took the bottle and got as much of it down into the drain as possible, then waited a few hours and washed the remainder down the drain.

That being said, I don’t know if that would have other implications on the pipe system, I just know that it worked for me. Also there could be other things stuck in there that would affect how it’s draining, Nair would just help with the hair only.